Deep Penetration Laser Welding (DPLW) is a technique for joining metals. It uses high-power lasers to shape and blend materials. This method is known for its accuracy, speed, and strength.

Deep penetration welding requires a high power density of about 1 MW per square centimeter. In this process, the laser beam melts the metal and creates steam.

The expansion of the hot water exerts pressure on the molten metal and causes its partial deformation. However, the metal is constantly melting. The result is a narrow, deep hole or keyhole filled with steam and surrounded by molten metal.

The keyhole moves through the workpiece as the laser beam passes over the weld joint. The molten metal flows around the keyhole, solidifying in its tracks. This results in a narrow, deep weld with a uniform internal structure. The weld depth can exceed ten times the width of up to 25 millimeters. The laser beam is repeatedly reflected on the keyhole walls. 

The molten material absorbs the laser light almost completely and improves the efficiency of the welding process. When a CO2 laser is used for welding, the steam inside the keyhole also absorbs the laser light and is partially ionized. This creates a plasma, which in turn transfers energy to the workpiece. Learn more. As a result, deep penetration welding stands out for its high efficiency and fast welding speed. Due to the higher velocity, the area affected by the heat and the variability are much smaller. This method is used for applications requiring deep welding or where several welding materials must be applied simultaneously.

How Does it Work?

Laser generation: 

A laser machine emits intense light.

Focusing the beam: 

When a lens or mirror is used, the beam is focused on a small area.

Penetration: 

Focused light heats the metal to a high temperature, causing the metal to melt and fuse.

Cooling:

The dry metal cools rapidly and hardens to form a solid weld.

Laser beam: 

The process begins with an intense laser beam that focuses on a small piece of metal to be collected.

Melting metal:

The laser’s intense heat causes the metal to melt in the target area. This creates a small, deep hole called a keyhole, which is surrounded by cast iron.

Fusion:

As the laser passes over the joint, the keyhole moves with it. The cold and hard molten metal behind the keyhole forms a strong bond.

Types of Lasers Used

Several types of lasers can be used for deep penetration laser welding. The most common are:

• CO2 Laser: This laser uses carbon dioxide gas to produce light. They are strong and are commonly used to weld mild steel.
• Fiber laser: This laser uses optical fibers to direct the beam. They work well and produce high-quality welds.
• Nd
• Laser: This laser uses a crystal called neodymium-doped yttrium aluminum garnet. They are versatile and can weld both metals and non-metals.

		Wavelength	Oscillation form
Gas	CO2 laser	10.6 μm	CWPulse
	TEA-CO2	Varies by gas pressure	Pulse
Solid-state	YAG laser	10.6 μm	CWPulse
	YVO4	10.6 μm	Pulse
Fiber	Yb fiber	975 nm	CWQ-switchUltra-short pulse
Semiconductor	Ld (laser diode) laser	1070 nm	CWPulse

Welding speed

With 10 kW laser power, +10 mm. Undercut and root sag defects were generated at welding speeds of 0.9 m/min and 1.2 m/min, respectively. At a welding speed of 0.9 m/min, the welding width is expanded by a shallow undercut due to the large amount of molten metal with excess heat input and the downward flow of water, including the core.

Benefits of Deep Penetration Laser Welding

• Accuracy: The laser can be accurately controlled, ensuring accurate welds. This is especially useful for small and complex parts.
• Speed: DPLW is faster than conventional welding methods. It can join metal in seconds, saving time in the manufacturing process.
• Strength: Welds made by DPLW are solid. They can withstand extreme stresses and are generally stronger than steel.
• Minimal distortion: The metal does not distort significantly because the laser heats a small area. This means that the original and original condition of the metal is maintained.

Applications of Deep Penetration Laser Welding

The accuracy and efficiency of deep penetration laser welding are used in many fields. Here are some of the most commonly used:

Automotive Industry:

Welding automotive parts such as engine parts and body parts. Strong welds ensure vehicles are safe and durable.

Aerospace Industries:

They are used to assemble aircraft and spacecraft parts. Accurate welds are essential to the performance and safety of these high-tech vehicles.

Medical Devices: 

They are used in the manufacture of medical devices and implants. Clean and accurate welds are critical to the performance and safety of medical devices.

Electronics: 

Weld small components in electronic devices. Laser welding’s precision contributes to the reliable and efficient production of electronic components.

Conclusion

Deep penetration laser welding is a powerful and versatile welding technique. Its ability to weld tightly and accurately makes it valuable in many applications. Whether for automobiles, airplanes, medical devices, or electronics, deep penetration laser welding is essential in ensuring product quality and durability.

Understanding how deep penetration laser welding works and how it is used can help businesses make the most of this advanced technology. By using suitable lasers and following the proper procedures, manufacturers can achieve high-quality welds that meet their needs.